Comparative assessment of microalgal fatty acids a

Authors: Sarah E Ruffell Kirsten M Müller Brendan J McConkey

Publish Date: 2015/09/01

Volume: 28, Issue: 3, Pages: 1695-1704

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Abstract

Bacteria are increasingly resistant to common antibiotics Certain fatty acids are effective antibacterial agents and when compared to conventional antibiotics have fewer incidences of bacterial resistance Algae naturally synthesize these fatty acids and can provide a sustainable source of these antibiotics To evaluate the antibacterial properties of fatty acids 29 acids present in algae were tested for topical antibacterial properties on Escherichia coli and Staphylococcus aureus using surface zone inhibition assay From the set of fatty acids showing good antibacterial activity five representative fatty acids—capric acid 100 palmitoleic acid 161 gammalinolenic acid 183 n6 arachidonic acid 204 n6 and docosadienoic acid 222 n6—were selected for further analysis Algal growth conditions light temperature and nutrients were manipulated to increase the content of the selected target fatty acids in five algal species Rhodella maculata Phaeodactylum tricornutum Boekelovia hooglandii Goniochloris sculpta and Chloridella simplex P tricornutum contained the highest content of the target antibacterial fatty acids with a maximum of 206 mg g−1 dry weight dw However biomass productivity was low thus for commercial viability initial growth should be under optimum conditions and then shifted to enhance antibacterial fatty acid content B hooglandii had the highest biomass productivity and a total antibacterial fatty acid content of 326 mg g−1 dw in Erddekokt + Salze + Peptone ESP medium 18 °C 80 μmol photons m−2 s−1 and 177h light/dark cycle This study identifies fatty acids that have effective antibacterial properties and potential use as topical antibacterial products and determined growth conditions that result in algae rich in these acidsWe are extremely grateful to Ms S Vesely at the University of Waterloo for her technical support throughout the experiment In addition we thank Dr Laura Dindia and Ms Maricor Arlos for their constructive comments This research was funded by NSERC discovery grants to KMM and BJM as well as a FedDev Ontario ARC grant Applied Research and Commercialization Initiative to KMM and BJM and matching ARC support from Algae Dynamics

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